The coenzyme, NAD+ (nicotinamide adenine dinucleotide) is reduced to NADH during glycolysis and it is used as a reductant for biofuel formation. We reported that mediated-electron transfer from a cathode to Clostridium and increased NADH/NAD+ ratio enhanced butyrate production without acetate (1). Here we show that the electroactive Clostridium used electrons directly from the cathode and determined final products depending on its current consumption. For the bioelectrochemical system (BES), graphite felt and platinum electrode were used for cathode and anode, respectively. The electrofermention was performed in the cathode compartment poised at -160 mV vs. Ag/AgCl. Electroactive Clostridium strain was inoculated with 30 g/L glycerol in cathode compartment. The current consumption increased by repeating batch electrofermentation and its product distribution was changed in BES: more electron consumption caused a shift of major product from butanol (NAD+/NADH balanced) to 1, 3-propandiol (one NADH need). Therefore, it suggested that electrochemically introduced reducing equivalent increased NADH/NAD+ ratio and enhance more NADH-consumption pathway in the Clostridium strain.